Motor-controller



W. F. LENT. MOTOR'C ONTROLL-ER; APPLICATION F lL ED-1UNE 21. 1916.

.1,347,863. w Patented July 27,1920,

25 means of UNITED- STATES "PATENT OFFICE.

WILMAR F. LENT, OF NEW YORK, N. Y.', ASSIGN'OR, TO THE CUTLER-HAMMER MFG' 00., OEKILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

MOTOR-CONTROLLER.

To all whom it may concern.'

Be it known that I, WILMAR F. LENT,a

citizen of the United States, residing at New of New York, have invented new and useful Improvements in Motor-Controllers, of which the following is a full, clear, concise, and exact description, reference beinghad to'the accompanying drawing, form1ng-a part of this specification.

1 This invention relates to motor controlers.

In the control of motor driven planers it is essential to insure against drifting of the planerbed throu h its limits upon failfie tripping of circuit objects to provide for planers and other devices efiicient and reliable braking means to meet such contingencies.

Further, the invention has for an object to provide means for effecting dynamic brakin of planers and other automatically reversi le devices bytheir driving motors regardless ofthe operation of the reversing such motors, as at the limits of a planer.

Other objects and advantages of the in- .vention will hereinafter appear.

One embodiment of the invention is diagrammatically illustrated in the accompanying drawing and the same will now be described, it being understood that the invention may be embodied in other forms falling within the scope of the appended claim.

he controller shown in the accompanying drawing is particularly applicable to planers and to the special type of driving motor M illustrated, said motor including an armature a, a series field winding f, an interpole winding f and a shunt f.

The controller is in general of conventional form. It includes an electro-responsivemain switch 1, and a mechanical device including reversing switches 2 and3and acceleratin switches 4, 5, 6 and 7. The reversing switc esareoperable selectivel byacam shaft 8 manually operable at wil and also adapted to be connected to the planer for reverse operations at the limits thereof,

while the switches 4 to 7 are operable in progression bya cam shaft 9 under the con trol of shaft 8. The shaft 9 is operable by a weight 10 to close the switches and by shaft 8 through a link 11 to open said I Patented July 27, 1920. Application filed June 21, 1916. Serial No. 104,841.

switches, the arrangement being such as to insure the opening of said switches upon 1n1t1a1 closure of either reversing switch while thereafter permitting said accelerating switches to close automatically. Accelerating sw1tches4, 5 and 6 control resistances 1', 1" and r for the motor circuit while the i switch 7 controls a short circuit around the series field f and a resistance 1' .The mechanical controller also includes auxiliary switches'12 and l3,'the former providlrig an interlock between said controller and the main switch and the latter controlling a short-circuit around field rheos tats 14 and 15. The switch 13 normally closes the shortcircuit aroundthe field rheostats and is operable by cam shaft 9 to interrupt said short circuit after closure of the accelerating switches. The rheostats 14 and 15 are further controlled by auxiliary contacts 2 and 3 of reversing switches 2 and 3 respectively to utilize the same selectively for reverse operations of the planer. controller includes a normally open push button switch 16 to energize the main switch 1 at will and a normally closed push button switch 17 to deenergize the main switch at will. 3

The control means described thus provides for setting the motor in operation and automatically reversing the same at the limits of movement of the planer bed, such reversals being-efi'ected'by reversal of the flow of current through the motor arma-- ture. Accordingly under normal conditions the power operation of the motor restrains theplaner against over-travel. But in the eventof failure of voltage or operation of the usual circuit breakers (not shown) such restraint by the motor is lost with conse- Still further, the

so i;

quent danger of over-travel of the planet v,

bed. Such over-travel, however, is positively precluded by the control means which will now be descrlbed.

The main switch 1 is provided with down contacts -1 which when in en tablish a local circuit across t e terminals of the motor armature including a resistance r. Also, the main switch 1 has associated therewith a normally closed auxiliary switch 1 which. establishes a local circuit across gementes:

the terminals of the shunt field f including a resistance r. Switch 1 is arran d to be engaged and opened by main switc 1 upon response of the, latter to complete the motor circuit and to reclose upon opening of said main switch. Further, the main switch has auxiliary contacts 1 controlling. the continuity of the shunt field circuitand serving to interrupt said circuit to cause the shunt field to discharge through the local circuit provided therefor by switch 1"; Still further, the main switch has auxiliary con tacts 1 to complete a maintaining circuit therefor through a high resistnce 1' which resistance may be so proportioned as to effect opening of the main switch upon "any I desired drop in voltage, as for example, a

drop to 80% of the normal line voltage.

Thus whenever the main switch opens it will establish a dynamic braking circuit for the motor and at the same time localize the shunt field discharge to maintain the excitaquick stop. In this connection it is also to be noted that if upon failure of voltage the counter voltage of the motor should tend to hold the main switch closed such tendency would be eliminated at the limits of the planer bed by the interruption of the m0- tor connections incident to reversal of the motor. The main switch would accordingly open immediately to efiect dynamic braking as described. On the other hand, so long as the planer bed does not drift to its limits the delay in the opening of the main switch is immaterial and in the case of a planer the friction quickly reduces the speed of the motor and hence its counter Voltage to a degree sufiicient to effect release of the main switchraccordin to the value of the resistance r. Mani estly therefore an eificient and reliable braking action b the motor is insured upon either failure 0 voltage, tripping of circuit breakers or operation of stopping switch 17 and regardless of the position of the planer or other driven device.

The circuit connections will now be described. With the line switch L, the main switch 1 and reversing switch 2 closed, circuit may be traced from line L by c0nductors 20 and 22 through resistance 1' by conductor 23 through resistance r and series field f, by conductor 24- through the right hand pole of switch 2, by conductor 25 through resistance 1', by conductor 26 through resistance r, by conductor 27 through the interpole winding f and armature a, by conductors 28 and 29 to and through the left hand pole of switch 2, by conductor 30 to and through main switch 1, by conductor 31 to line L Also, circuit may be traced from line L by conductors 20, 32 and 33 through switch 13, by conductors '34 and 35 through the shunt field winding, by conductor '36 through contact 1 of main switch 1 to conductor 31 and thence to line L The connections thus provide for starting the motor with full field strength and it will be assumed that said connections effect operation of the planer in working direction. Following establishment of such connections the switches 4, 5 and 6 respond. progressively to exclude the resistances r, r and r from the armature circuit and thereupon switch 7 responds to short circuit the series field and resistance 1' by the connections which are obvious. Finally the switch 13 is opened whereupon the current supplied to the field is forced to take a path from conductor 32 by conductors- 37 and 38 through the auxiliary contacts of switch 2, by conductors 39 and 40 through rheostat 14 to conductor 35 and thence through the field as already described. On the other hand, with the switch 2 open '-a'nd switch 3 closed the armature connections. are reversed: resistance r is excluded from said connections. Under such conditions -circuit extends from conductor 20 through resistances 1' and r 'and through the series field in the same direction as above described to conductor 24 and thence through the right hand pole of switch 3 to-conductor 28 and through the armature and interpole field in a reverse direction to that previously described, to conductor 27 through resistance 1", by conductor 26 through the left hand pole of switch 3, by conductor 30 and thence through the main switch 1 to line L The initial field connections are the same as described but when switch 13 is opened the field circuit is shifted to rheostat 15 instead of rheostat 14. Under such conditions the field circuit extends from conductor 32 through rheostat 15 by conductors 41, 40 and 42 through the auxiliary contacts 3*.of switch 3, by conductor 43 to conductor 35 and thence through the field as described.

The energizingilcircuit of main switch ex-' tends from line by conductor 20 to and through the auxiliary contacts 12 of the mechanical controller by conductor 44 through push button switch 16, by conductor 45 through push button switch 17, by conductor 46 through the windin of main switch 1 to conductor 31 and line T When, however, the mechanical controller operates it breaks circuit at its contacts 12 thereby throwing the main switch onto its maintaining circuit. This maintaining circuit extends from line L by conductors 20 and 47 through resistance '1', auxiliary contacts 1 of the main switch, by conductor 4.8 to conductor 7 is in runmng position it cannot be energized until such controller is returned to off position to reengage its auxiliary contacts 12.

The dynamic braking circuit established by the main switch varies according to the reversing switch which is closed at the time.

' pole field to lVith switch 2 closed the dynamic braking circuit may be traced from the right handterminal of the motor armature by conductors 28 and 29 to and through the left hand pole of switch 2, by conductor 30 through down contacts 1 of the main switch, and through resistance 7", by conductors 50 and 24: to and through the right hand pole of switch 2 and by conductor 25 through resistance r, by conductor 26 through resistance 7", by conductor 27 through the interthe left hand terminal of the armature. On the other hand with the switch 3 closed the braking circuit ma be traced from the right hand terminal 0 the armature by conductor 28 through the right hand pole of switch 3, by conductors 24 and 50 through resistance 1" and the down con-i tacts 1 of the main switch, by conductor 30 through the left hand pole of switch 3, by conductor 26 through resistance 1", by conductor 27 through the interpole field f through the left hand terminal of the armature. pendent of the reversing switches and may be traced from the right hand terminal of .the field by conductor 36 to and through of the main switch, by-

auxiliary switch 1 conductor 51 to and through resistance 1' to the left hand terminal of said field.

What I claim as new and desire to secure by Letters Patent is:

In a controller for an electric motor having a shunt field winding, an electro-responsive switch responsive to establish power circuits for both the motor armature and shunt field winding and releasable upon failure of voltage to interrupt said circuits, means to increase the resistance of the circuit of said switch after response thereof to increase its sensitiveness to voltage reductions and means controlled by in combination,

The field discharge circuit is inde--85 said switch to establish local circuits for the 7 In witness whereof, I have hereunto subscribed my name.

WILMAR F. LENT. 

